Netronics ELF II recovery


This Web page last updated Jan 9 2020. copyright Herb Johnson (C) 2020. . In June 2019, I curated an ELF II computer with documents and cassette-based software. "Curated" means I've cataloged the collection of items around it and I'm providing some interpretation. I"ve scanned many of the hardware documents, and I'm copying the audio-data cassette tapes to WAV files. The computer and materials were donated by George Musser in Dec 2017, to the Vintage Computing Federation museum in Wall NJ at InfoAge. I borrowed them in June 2019 with permission, to continue the digitizing work on tapes and documents. The digitizting was completed in Oct 2019. Thanks to Marcel von Tongeren's personal work and his EMMA 02 COSMAC emulator, the digitized tapes are or will be available again as tested binary files. - Herb

ELF II hardware as donated


I did not initially curate (examine) the ELF II in any detail. I looked it over on Dec 2017 and took a few photos then. Here's a photo of the boards on the ELF II backplane. Looking under the plexiglass box, you can see the ACE bus adapter board, and some ACE board plugged into it. The ELF II system was supported by this ASCII keyboard.

IN June 2019 I created this list of hardware and boards.

Netronics ELF II (the chassis and upper backplane)
Netronics AD-1 power supply (outside cabinet, in documentation box)
Netronics ASCII-A2 keyboard (outside of cabinet of course)
Netronics "Giant" board (ROM and I/O ports)
Netronics 16K RAM boards, two different
Netronics PROM Programmer
Netronics 4K board (not in system)
Netronics Full BASIC Math/ROM board , w/ National 57109 calculator chip

ACE NAB Netronics adapter board/backplane
ACE (8k?) VDU board (in ACE backplane) with Motorola 6847 video chip, 16K RAM

Regarding issues of copyright and permissions, please check the linked information.



A partial list of documents as donated with this system. As of June 2019 most of these not available elsewhere, have been scanned. I will work to make PDFs of these available, when they are not available elsewhere. Look on this Web page for links to other sites with these or similar documents. Or of course, use Web search. Regarding issues of copyright and permissions, please check the linked information. - Herb

"A short course in programming" by Tom Pittman, for Netronics (c) 1976. available on the tinyBASIC Web site of Tom Pittman.

Moews program documents, previously digitized by ??? and made available on the Web by Matthew Mikolay with permission by Moews.
Paul C Moews - Programs for the COSMAC ELF interpreters
Paul C Moews - Programs for the COSMAC ELF graphics
Paul C Moews - Programs for the COSMAC ELF music and games (rev. 4)

Notes on games produced by Donald Richard Shroyer.
Cassette chess, Breakout, Star Trek.

"Game Pak #1", unknown producer. Tic-Tac-Toe, Tank Warfare, Animal Race, Acey Deucey.

George Musser, "Text Editor Modifications". Based on program "Scriptory" in Ipso Facto #23 by Steve Nies and other programs.

Quest - Video Graphics Software Package
Quest - flyers for products
QuestData - newsletters,, vol 1 6-12, vol 2 1-5, 9-11, vol 3 1-3
Available on the Web site as publications: newsletters. Quest documentation is available to members of the discussion group "cosmacelf". There's other archives too.

IPSO FACTO newsletters
- Vol I (issues 1-6), Vol II (7-12), Vol III (13-18)
- issues 19 thru 36
Previously available and indexed on the Web site. There's other archives too. A number of Netronics boards and software are described in these newsletters, by Tom Crawford.

RCA publications: MPM 206, MPM 201B, VP-511, VP-720, VP-710, VIP-311. Likely available elsewhere on the Web, such as and Github/ajavamind. Also, RCA SSD data-sheets for the 1805 (#1309), 1804 (#1147), 1802D (#1023), 1861 (preliminary).

"Superbasic, V5.0" by Ron Cenker (manual)

Netronics ELF II manuals: I've PDFed most of these. Some can or will be found in COSMAC archives at cosmacelf in (was at Yahoo). Some may also appear at the file archives.

The documents in this collections are:

	Giant board
	4K board
	16K board
	ASCII-A2 keyboard
	1802/1804 full BASIC Math/Rom board
	EPROM programmer - 2716
	AD-1 Power Supply
	Tiny BASIC User Manual
	Video Graphics Software Package

data sheet for National 57109 numeric processor. Courtesy of Also, an IPSO FACTO article about Netronics BASIC and the math coprocessor. (These were not part of this ELF II documentation.) Follow this link for more discussion about this and other "math coprocessors".

Regarding issues of copyright and permissions, please check the linked information.

Netronics promotional materials; mailer, ads.

ACE (Association of Computer ??) produced the Ipso Facto newsletters, and produced some ELF II support products under the ACE brand. HEre's some ACE documents provided with this ELF II.

ACE NAB-2 Netronics adapter board, manual
ACE Backplane, manual
ACE VDU board, manual

note on ACE VDU board: from Marcel van Tongeren, Jan 2020: "As far as I have figured out from the manual and the code of different SW, this is how it works:

The 6847 video mode is set by writing to address FFxx and bit 6/7 in video memory.
A/S is linked to bit 6 and INV to bit 7 of video memory.
CSS is bit 1, INT/EXT bit 2, A/G bit 4, GM0-GM2 bit 5 to 7 of address FFxx.

I know the manual states FF00 but when looking into the code all set R1.1 to FF but donít set R1.0 before storing the mode byte. As R1.0 will as such be undefined, it could be anywhere in the FFxx page. Makes sense as well, as it is probably less HW then decoding the full 16 bit address. Guessed a bit with the FFxx bits as well but it looks like it matches the schematics and notes made by owner of the manual." - Marcel

audio cassettes for data storage


These are mostly user-recorded audio cassettes, mostly in user-labled cases. Cassette may not match label. Most cassettes have contents listed on cassette label, some have no listing. Multiple listings means multiple tapes.

labeled cases:

VDU programs
Game Pack #1
Game Pack #2
Game Pack #3
super BASIC programs
super BASIC programs
super basic programs
game / TV files
[prerecorded] Quest Super Basic V5.0
[prerecorded} ELF Bug
[head cleaning cassette]

unlabeled cases: monitor super BASIC 0000-24FF Album countdown F&L Sub1 2/24/76

recovery of binaries from ELF II tape collection


Summary of tape activities

Background on the use of audio cassettes for data storage is discussed on the linked Web page. Specific information on the ELF II cassette format is on this linked Web page.. Here's an Ipso Facto article on the ELF II cassette "standard".

During a June 2019 VCF repair workshop, at the VCF facilities at InfoAge, I gathered the ELF II documents and tapes, made a quick paper catalog of them. With the Dell laptop and Realistic audio-tape cassette player as shown, I used the Audacity software package to produce a reasonable WAV file of each side of one cassette. As described later on this Web page, the two WAV files were examined, verified and decoded by Marcel von Tongeren (Emma 02 creator).

With that verification of methods established, in Oct 2019 I digitized most of the remaining tapes to WAV files. Marcel decoded almost all of them back to binaries. With his EMMA 02 emulator - now with more documentation of the ELF II and ACE VDU hardware from this archive - he was able to operate many of the binaries under emulation.

Recovered binaries

As of Jan 2020, these will be released soon. Marcel is doing some work on his EMMA 02 emulator to improve support of the ELF II's VDU board. If other archives are established, I'll add references to them.

From Marcel von Tongeren, Jan 7 2020: "I have started with the VDU [board with MC6847 graphics] games from your [ELF II] collection. I did have full emulation implemented [under Emma 02]. However it didnít work, as I had never fully tested it, due to lack of SW using some of these graphic modes. Now, I have it running."

"Most of the VDU games use graphic mode íSemiGraphics 4í and I also found two which use the 128*64 RG1 mode, tiny basic uses the alphanumeric mode. I have added some notes in the [text file] doc. One strange thing is that none of the games/SW executes any ĎOUTí instructions to set a specific graphic mode. So I am not sure how this was done on the real thing. [The VDU manual says program location F000H. - Herb] I will now start going thru the [binaries as] collected again and see what SW I donít have in the Emma 02 [ELF II and other] archives, and add anything missing for release in the next version. - Cheers, Marcel"

Here's the list of recovered binaries, by original cassette tape, and programs recovered, and as zipped up, with some notes. I'll try to keep this file updated; currently it's based on early Jan 2020 work. Regarding issues of copyright and permissions, please check the linked information. - Herb

recording and decoding tapes

JUne 2019 Cataloging of tapes, test digitizing


The cassette was boxed in a "miscelaneous" labled box; the cassette itself is labled "games". Both box and cassette is as shown. Here's an Audacity view of the digitized results. See a recorded waveform (background) and a frequency analysis of the results (foreground). Note the frequency peaks at roughly 3300 Hz and around 900 Hz. (Subsequent measurements suggest 750Hz and 2300Hz; the Ipso Facto article uses analog measurements and finds 800Hz and 2400Hz).

As discussed on the linked Web page about data recovery from RCA/Sarnoff COSMAC tapes, the goal was to digitize an audio tape, to produce digitized waveforms of fairly consistent peak value and as "smooth" as reasonable. That amounts to high-pass filtering to boost higher frequencies, again as discussed in the linked Web page.

Practically, for binary detection from the digitized data, one wants clean zero-crossings. The ELF II hardware and software measures off frequency duration between zero-crossings to determine ones and zeros. This linked Web page discusses an example for the RCA VIP computer, another 1802 COSMAC computer.

In June 2019, I obtained the ELF II tapes for digitizing. That summer I verified two digitized tapes could be decoded by Marcel von Tongeren; then I digitized the rest and he decoded them back to COSMAC binaries. With his Emma 02 emulator's version of the ELF II plus repairs to his software emulation of it, he was able to verify the operation of those binary programs. He will make those programs available with his Emma 02 emulator. - Herb

June 2019 test of "miscelaneous" cased tape

On June 2019 at a Vintage Computing Federation - Midatlantic repair workshop, I digitized two sides of one of the ELF II collection tapes, and processed it as I'll describe.

Side 1 WAV file and Side 2 WAV file of the tape in the "miscelaneous" case and physically labled "music" on the cassette. And here's a JPEG of the case and cassette. This text file describes the tape and paper labeling, and analysis with Audology tools. Here's an Audacity view of Side 1 digitized results.

This Web page about "FRED" type COSMAC cassettes, includes a binary description of the WAV file header. The header of side 1 looks like this:

Offset      0  1  2  3  4  5  6  7   8  9  A  B  C  D  E  F

00000000   52 49 46 46 A8 E2 D5 00  57 41 56 45 66 6D 74 20   RIFF®‚’.WAVEfmt 
00000016   10 00 00 00 01 00 01 00  22 56 00 00 44 AC 00 00   ........"V..D¨..
00000032   02 00 10 00 64 61 74 61  C0 E1 D5 00 D0 FE C2 FE   ....dataņŠ’.–Ģ¬Ģ

Decoding by hand, the WAV file consists of PCM encoded, mono (one track), 5622x (22050d) samples/sec, AC44x (44100d) sample rate, 2 channels, 16d bits per sample.

Results for "miscelaneous"


I provided the two WAV files of the "miscelaneous" tape, to Marcel Van Tongren, the developer of the EMMA 02 COSMAC emulator. In early June 2019, he successfully ran the WAV files through his emulator, decoded out the programs, and partially operated them. Here's the decoded programs and some program notes. Also, here's general notes about the tape and programs. The programs were mostly named on the case of the tape and are as below. Unlisted programs are in []'s.

side 1 cassette loader 0:00 - 0:08 cosmac cosmos (0000-08ff) 0:35 -1:04, may be short of data, 0FFF? blockade (0000-08ff) 1:16- 1:52 video animation (0000-0fff) 1:58 -2:52, signal drop at 2:13-2:14 cosmac cowboy (0000-03ff) 2:58 - 3:22 [overwritten program] 3:24 - 3:55 side 2 cassette reader 0:00 - 0:15 VIPII? morse code (0000-08ff) 0:22 - 1:00 VIPII? dogfight (0000-0fff) 1:04 - 1:56 CHIP8 miniature golf (0000-0fff) 2:03 - 2:56 CHIP8 dot-dash (0000-0fff) 3:06 - 4:02 CHIP8 [space invaders (0000-0FFF)] 4:08 - 5:03

Copyrights and releases

Regarding Quest materials, the following is a statement produced by Steve Gemeny after previous Quest materials were reproduced and previously provided on the cosmacelf Web site. - Herb

"In order to avoid any discussion of the validity of this position, the [Quest] material is being released under the Creative Commons License with attribution to Roger Pitkin as granted to all holders of Quest Electronics Copyrighted material by Roger Pitkin Ė Founder and Owner of Quest Electronics, Nov., 2010 (via Email to & communicated to the yahoo cosmacelf group)." - Steve Gemeny, Yahoo CosmacELF group member, AA3NM

Regarding Netronics Inc. materials, I believe George Meyerle of Netronics, Ltd. retains copyrights for those materials.

Regarding ACE, the Association of Computer Experimenters; I do not know the current copyright status of their materials. "The Association of Computer Experimenters was a Canadian 1802 users group, founded in 1977 through the efforts of Tom Crawford and Eugene Tekatch." They were a non-profit educational organization. They published Ipso Facto and provided kits and products. One can find an archive of Ipso Facto newsletters on the Web site.

Regarding Paul C Moews works: they contain the following copyright statement or dated variations: "Copyright © 1979 by Paul C. Moews; All rights reserved; Published March, 1979 by Paul C. Moews; Printed by Parousia Press, Storrs, Connecticut"

I"ll be glad to accomodate within reason, requests of copyright holders to modify these statements of copyrights. - Herb Johnson

Copyright © 2020 Herb Johnson

Herb Johnson
New Jersey, USA
to email @ me follow this link